Tamper resistant closure

Abstract

A method and apparatus for forming a tamper resistant seal on a plastic bag containing a loaf of bread or other products is disclosed. The neck of the bag is flattened, gripped between a pair of lower inboard and out board gathering belts adjacent opposite sides of a segment of the neck of the bag. A row of perforations is formed in the bag neck as the bag moves adjacent a roller provided with teeth or cutting elements. Heated air jets are directed to engage the segment of the bag bridging between the inboard and the outboard of the bag bridging between the inboard and the strip from the bag.

1. A method of forming a tamper evident seal on a plastic bag containing a loaf of bread comprising the steps of:
 flattening a portion of the neck of the bag adjacent the open end of the bag;  
 positioning a segment of the flattened portion to bridge between spaced grippers;  
 forming a row of perforations in the bag neck;  
 directing heated air jets to engage the segment of the bag bridging between the spaced grippers for fusing panels of the bag together to form a sealed strip spaced from the row of perforations in the bag neck to facilitate removal of the sealed strip from the bag, wherein the row of perforations in the bag neck is formed before the heated air jets engage the neck of the bag to assure that the bag is perforated while it is cool and before it is heated to the point at which it might tend to stretch and deform while perforations are being formed, and wherein the air impinges against the portion of the bag bridging between the spaced grippers such that the molten plastic or any ink which may be softened by the heated air is not offset onto the grippers or any other mechanism before the neck of the bag is cooled;  
 gathering the flattened portion of the bag between the sealed segment and the loaf of bread; and  
 attaching a reusable closure to said neck.  
 
   
   
     2. A method of forming a tamper evident seal on a plastic bag having a neck, with ink on the neck of the bag that may be softened by heat, and sides welded together to render the contents of the bag accessible containing a loaf of bread comprising the steps of:
 flattening a portion of the neck of the bag adjacent the open end of the bag;  
 positioning a segment of the flattened portion of the neck of the bag such that it bridges space between horizontally spaced grippers;  
 heating the portion of the neck of the bag that it bridges space between spaced grippers to a temperature sufficient for bonding material forming the neck of the bag for forming a sealed segment such that the contents of the bag are not accessible;  
 gathering the flattened portion of the bag between the sealed segment and the loaf of bread; and  
 attaching a reusable closure to said neck, wherein the step of heating the flattened portion of the bag comprises the steps of:  
 delivering air heated to a temperature in a range between about 315° and 600° Fahrenheit in a stream to impinge against the surface of the bag; and  
 gripping portions of the bag adjacent opposite sides of the segment of the bag against which the stream of air impinges, and wherein the air impinges against the portion of the bag bridging between the spaced grippers such that the molten plastic or any ink which may be softened by the heated air is not offset onto the grippers before the neck of the bag is cooled.  
 
   
   
     3. A method for forming a tamper evident closure on a plastic bag containing a product said bag having an open end forming a neck extending beyond a product in a bag comprising the steps of:
 forming a row of perforations across the neck of the bag between the product in the bag and the open end of the bag neck;  
 gripping the bag at spaced positions adjacent opposite sides of the row of perforations; and  
 directing temperature controlled air to impinge against the bag between the gripped positions for forming a sealed strip between the row of perforations and the open end of the bag, wherein the air impinges against the portion of the bag bridging between the spaced gripped portions such that molten plastic which may be softened by the heated air is not offset onto the grippers before the neck of the bag is cooled.  
 
   
   
     4. Apparatus for forming a tamper evident closure on a plastic bag containing a product comprising:
 means for gripping spaced portions of the bag;  
 means for forming a row of perforations in the bag adjacent the gripped portions of the bag; and  
 means for delivering temperature controlled gas to impinge against the surfaces of the bag between the gripped portions for fusing portions of the bag between the gripped portions for forming a sealed strip, said perforations being positioned to permit removal of the sealed strip, said means for forming a row of perforations in the bag and said means for delivering temperature controlled gas to impinge against the surfaces of the bag being spaced apart such that the air impinges against the portion of the bag bridging between the spaced gripped portions such that molten plastic softened by the heated air is not offset onto the means for gripping spaced portions of the bag before the sealed strip is cooled.  
 
   
   
     5. Apparatus for forming a tamper evident closure on a plastic bag according to  claim 4  said means for gripping spaced portions of the bag comprising a pair of horizontally spaced upper belts and a pair of horizontally spaced lower belts, said horizontally spaced upper and lower belts being arranged to engage spaced portions on the neck of a bag such that the neck bridges space between the belts. 
   
   
     6. Apparatus for forming a tamper evident closure on a plastic bag according to  claim 4  said means for forming a row of perforations in the bag adjacent the gripped portions comprising an anvil having a slot formed therein adjacent one side of the neck of the bag and a perforator wheel having cutter teeth positioned adjacent the other side of the bag neck such that said teeth perforate the bag and extend into the slot formed in the anvil when a bag neck moves between the anvil and the perforator wheel. 
   
   
     7. Apparatus for forming a tamper evident closure on a plastic bag according to  claim 4  said means for delivering temperature controlled gas to impinge against the surface of the bag comprising an upper manifold positioned above the neck of the bag and a lower manifold positioned below the neck of the bag; and means for delivering air through said upper and lower manifolds for impinging against the neck of the bag, said air being heated to a temperature sufficient for melting the bag neck for forming a sealed strip extending generally parallel to said row of perforations. 
   
   
     8. Apparatus for forming a tamper evident closure on a plastic bag according to  claim 7  with the addition of a diverter valve adjacent each of said upper and lower manifolds, said diverter valve being actuatable to divert air flow from said upper and lower manifolds and to exhaust air, without interruption of the flow of air into the diverter valves. 
   
   
     9. Apparatus for forming a tamper resistant closure on a plastic bag containing a product comprising:
 a conveyor for moving a plastic bag containing a product along a path, said bag having an open end forming a neck extending beyond the product in the bag;  
 an air nozzle for flattening the open neck as the bag is moved by said conveyor;  
 a pair of upper brushes and a pair of lower brushes, a first of said pair of upper and lower brushes having bristles arranged to engage the flattened neck of the bag and draw the bag transversely across said conveyor, second upper and lower brushes having angularly inclined bristles for moving the leading edge of the bag neck longitudinally of the conveyor while the trailing edge of the bag neck is engaged by the first upper and lower brushes;  
 a pair of upper belts and a pair of lower belts, said upper and lower belts being horizontally spaced apart such that one of said upper belts and one of said lower belts engage opposite sides of a portion of the neck of the bag and one of said upper belts and one of said lower belts engage a second portion of said bag neck such that a portion of the bag neck bridges space between the upper pair of belts and the lower pair of belts;  
 a perforator wheel adjacent one side of said bag neck and an anvil having a slot formed therein adjacent the other side of the bag neck, said perforator wheel forming a row of perforations in the neck of the bag moved by said upper and lower belts; and  
 upper and lower air dispensers positioned to deliver heated air to impinge against upper and lower surfaces of the portion of the bag neck bridging between the belts for melting and forming a sealed strip across the entire width of the bag neck for forming a seal extending generally parallel to the row of perforations formed in the bag neck.  
 
   
   
     10. Apparatus for forming a tamper evident closure on a plastic bag containing a product comprising:
 a conveyor for moving a plastic bag containing a product along a path, said bag having an open end forming a neck extending beyond the product in the bag;  
 means for flattening the open neck as the bag is moved by said conveyor;  
 a pair of upper belts and a pair of lower belts, said upper and lower belts being horizontally spaced apart such that one of said upper belts and one of said lower belts engage opposite sides of a portion of the neck of the bag and one of said upper belts and one of said lower belts engages a second portion of said bag neck such that a portion of the bag neck bridges space between the upper pair of belts and space between the lower pair of belts;  
 a perforator wheel adjacent one side of said bag neck and an anvil having a slot formed therein adjacent the other side of the bag neck, said perforator wheel forming a row of perforations in the neck of the bag moved by said upper and lower belts;  
 an upper manifold positioned above the neck of the bag and a lower manifold positioned below the neck of the bag, said manifolds being positioned to deliver heated air to impinge against upper and lower surfaces of the portion of the bag neck bridging between the belts for melting and forming a sealed strip adjacent a row of perforations, said seal strip being a seal that can be torn from the bag along the row of perforations; and  
 a diverter valve adjacent each of said upper and lower manifolds, each said diverter; valve being actuatable to divert air flow from said upper and lower manifolds and to exhaust the diverted air, without interruption of the flow of air into the diverter valves.  
 
   
   
     11. Apparatus for forming a tamper evident closure on a plastic bag containing a product comprising:
 gripper means for gripping spaced portions of the bag neck on an open end of a bag such that the neck bridges between the gripper means;  
 an upper manifold positioned above the neck of the bag and a lower manifold positioned below the neck of the bag, said manifolds being positioned to deliver heated air to impinge against upper and lower surfaces of the portion of the bag neck bridging between the gripper means for melting and forming a sealed strip, said sealed strip being a seal that makes it evident if the bag has been opened;  
 a diverter valve communicating with each of said upper and lower manifolds, each said diverter valve being actuatable to divert air flow from said upper and lower manifolds and to exhaust the diverted air, without interruption of the flow of air into the diverter valves.